Bi-directional neuron-electronic device interface structures

ABSTRACT

An interface structure for a biological environment including at least one composite electrical impulse generating layer comprising a matrix phase of a piezo polymer material, a first dispersed phase of piezo nanocrystals, and second dispersed phase of carbon nanotubes, the first and second dispersed phase presented through the matrix phase. The piezo polymer material and piezo nanocrystal convert mechanical motion into electrical impulses and accept electrons to charge the composite impulse generating layer. The carbon nanotubes provide pathways for distribution of the electrical impulses to a surface of the composite impulse generating layer contacting the biological environment. The carbon nanotubes further provide for the delivery of the byproducts of the free radical degradation from the biological environment to both piezo-nanocrystals and piezo-polymer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/452,892 filed Jan. 31, 2017, titled “A sustainable self-poweredbi-directional neuron-silica interface technology”, which isincorporated herein in its entirety by reference.

BACKGROUND Technical Field

The present invention generally relates to interfaces with biologicalenvironments that can create as well as transmit electrical impulses, aswell as receive electrical impulses from the biological environment, andmore particularly to interfaces composed of piezoelectric materials andnanostructures.

Description of the Related Art

The interaction between the biological systems and mechanical orelectrical machines has been in the interest of mankind for centuries.With the discovery of electricity and electric properties of nerves andmuscles, there had been numerous attempts to make a functional interfacebetween the body and the machine or an artificial/prosthetic device.

Deep brain stimulation (DBS) is an approach to address the issue of thesubstitution of the loss of function in neurological diseases such asParkinson's disease. Current DBS devices are electrical devicesconsisting of 2-4 electrodes implanted in the brain and wired to aportable battery-powered device usually implanted in the chest area. Thebattery is placed under the skin of the chest. The routine batterychange is every 5+ years. Maintenance, replacement, and possiblehardware malfunction are associated with the risk of medicalcomplications.

SUMMARY

The methods and structures described herein can provide aneuron-computer bi-directional interface material. The interfacematerial layer include of a sustainable self-powered composite polymerwith embedded nano-crystals and carbon nano-tubes for integration in aneuron-glial network. The neuron-computer bi-directional interfacematerial can be used as a stimulator of excitable tissue, and can beused as interface for functional prosthetics.

In accordance with an embodiment of the present invention, an interfacestructure is provided for transmitting to and receiving electricalimpulses from a biological environment. In some embodiments, theinterface structure may include at least one composite impulsegenerating layer comprising a matrix phase of a piezo polymer material,a first dispersed phase of piezo nanocrystals, and second dispersedphase of carbon nanotubes, the first and second dispersed phasepresented through the matrix phase, wherein the piezo polymer materialand piezo nanocrystal convert mechanical motion into electrical impulsesand accept electrons to charge the composite impulse generating layer,and the carbon nanotubes provide pathways for distribution of theelectrical impulses to a surface of the composite impulse generatinglayer contacting the biological environment, and the delivery of freeradicals from the biological environment to at least the piezonanocrystals, or piezo elements including piezo nanocrystals and piezopolymer.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description will provide details of preferred embodimentswith reference to the following figures wherein:

FIG. 1 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multi-layered structure including a compositelayer of a piezo polymeric matrix material, a first dispersed phase ofpiezo nanocrystal material, and a second dispersed phase of carbonnanotubes, and at least one biological environment interface layerhaving a grid geometry, in accordance with one embodiment of the presentdisclosure.

FIG. 2 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multi-layered structure including a compositeelectrical impulse generating layer; a composite electrical impulseamplifying layer, and at least one biological environment interfacelayer having a grid geometry, in accordance with one embodiment of thepresent disclosure.

FIG. 3 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multi-layered structure including a compositeelectrical impulse amplifying layer positioned between two compositeelectrical impulse generating layers; and at least one biologicalenvironmental interface layer having a grid geometry, in accordance withone embodiment of the present disclosure.

FIG. 4 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multilayered stack including a compositeelectrical impulse generating layer, a composite electrical impulseamplifying layer, a piezoelectric composite layer free of carbonnanotubes, a resin layer and a biological environmental interface layer,in accordance with one embodiment of the present disclosure.

FIG. 5 is a perspective view of another embodiment of a neuron-computerbi-directional interface structure having a film and ribbon form factor,in which the interface structure is a multilayered stack including afirst biological environmental interface layer, a first resin layer, afirst piezoelectric composite layer free of carbon nanotubes, a firstcomposite electrical impulse amplifying layer, a composite electricalimpulse generating layer, a second composite electrical impulseamplifying layer, a second piezoelectric composite layer free of carbonnanotubes, a second resin layer and a second biological environmentalinterface layer.

FIG. 6 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multi-layered structure including a compositelayer of a piezo polymeric matrix material, a first dispersed phase ofpiezo nanocrystal material, and a second dispersed phase of carbonnanotubes; a dielectric polymer layer; and at least one biologicalenvironment interface layer having a grid geometry, in accordance withone embodiment of the present disclosure.

FIG. 7 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure is a multi-layered structure including a dielectricpolymer layer positioned between two composite electrical impulsegenerating layers; and at least one biological environmental interfacelayer having a grid geometry, in accordance with one embodiment of thepresent disclosure.

FIG. 8 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor in the geometryof a haphazard ribbon.

FIG. 9 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor in the geometryof a mobious loop.

FIG. 10 is a perspective view of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor in the geometryof a coil.

FIG. 11 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor in the shapeof a sphere having a plurality of spikes/columns extending from theouter surface of the sphere.

FIG. 12 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor in the shapeof a sphere having a nucleus present within an outer sphere.

FIG. 13 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor in the shapeof a sponge, in accordance with one embodiment of the presentdisclosure.

FIG. 14 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor in the threedimensional blot, in accordance with one embodiment of the presentdisclosure.

FIG. 15 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor having a wiretype geometry, in accordance with one embodiment of the presentdisclosure.

FIG. 16 is a perspective view of a neuron-computer bi-directionalinterface structure having a three dimensional form factor having ageometry including multiple wires, in accordance with one embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and materials aredisclosed herein; however, it is to be understood that the disclosedembodiments are merely illustrative of the claimed structures andmethods that may be embodied in various forms. In addition, each of theexamples given in connection with the various embodiments are intendedto be illustrative, and not restrictive. Further, the figures are notnecessarily to scale, some features may be exaggerated to show detailsof particular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a representative basis for teaching one skilled in the art tovariously employ the methods and structures of the present disclosure.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment. For purposes of thedescription hereinafter, the terms “upper”, “over”, “overlying”,“lower”, “under”, “underlying”, “right”, “left”, “vertical”,“horizontal”, “top”, “bottom”, and derivatives thereof shall relate tothe embodiments of the disclosure, as it is oriented in the drawingfigures. The term “positioned on” means that a first element, such as afirst structure, is present on a second element, such as a secondstructure, wherein intervening elements, such as an interface structure,e.g. interface layer, may be present between the first element and thesecond element. The term “direct contact” means that a first element,such as a first structure, and a second element, such as a secondstructure, are connected without any intermediary conducting, insulatingor semiconductor layers at the interface of the two elements.

The methods and structures described herein can provide aneuron-computer bi-directional interface material that can include of aself-powered composite polymer with embedded nano-crystals and carbonnano-tubes. The neuron-computer bi-directional interface material can beused as a stimulator of excitable tissue, e.g., brain tissue, spinalcord tissue, peripheral nerves, skeletal and heart muscles, etc., andcan be used as interface for functional prosthetics and brain computerinterface devices, including but not limited to, biorobotic,exoskeletons, and implantable devices.

In some embodiments, the self-powered composite polymer provides thatthe interface material be a flexible, as well as stretchable,piezoelectric energy harvesters that can harvest minute biomechanicalmotions in human body and transduce it into electric impulses/current.Such technology can be further used in self-powered sensitivepiezoelectric medical devices. More specifically, in some embodiments,to provide the self-powered aspect of the composite structure, electricimpulses are generated in the composite polymer with embeddednano-piezo-elements through the transduction of mechanical movement intoelectromotive force (EMF). The EMF will generate an electric currentutilized by adjacent neurons to facilitate cell membrane depolarizationand further propagation of the action potential along theneuronal/axonal network.

The conversion of mechanical movement into electromotive force (EMF)results from piezo-electric effects produced from both a piezo polymermaterial that provides the matrix material for an interface structurefor transmitting and receiving electrical impulses from a biologicalenvironment, and piezo nano crystals that are a dispersed phase that canbe present throughout an entirety of the matrix material. Piezo-electriceffects, i.e., piezo-electricity, is based on the ability of a material,e.g., crystal, to generate an electrical charge when mechanically loadedwith pressure or tension, which is called the direct piezo effect.

A piezoelectric polymer is a material having piezoelectricity, i.e., theability of material, which is the property that the polarization of amaterial change by applying stress and/or strain generated by changingpolarization). The piezoelectric polymer provides the matrix of acomposite structure. A composite is a material composed of two or moredistinct phases, e.g., matrix phase and dispersed phase, and having bulkproperties different from those of any of the constituents bythemselves. As used herein, the term “matrix phase” denotes the phase ofthe composite that is present in a majority of the composite, andcontains the dispersed phase, and shares a load with it. In the presentcase, the matrix phase may be provided by a polymer.

The word “polymer” can be defined as a material made out of a largenumber of repeating units which are linked to each other throughchemical bonding. A single polymer molecule may contain millions ofsmall molecules or repeating units which are called monomers. Polymersare very large molecules having high molecular weights. Monomers shouldhave a double bond or at least two functional groups in order to bearranged as a polymer. This double bond or two functional groups helpthe monomer to attach two more monomers, and these attached monomersalso have functional groups to attract more monomers. A polymer is madein this way and this process is known as polymerization. The result ofpolymerization is a macromolecule or a polymer chain. These polymerchains can be arranged in different ways to make the molecular structureof a polymer. The arrangement can be amorphous or crystalline. The maindifference between amorphous and crystalline polymers is their moleculararrangement. Amorphous polymers have no particular arrangement or apattern whereas crystalline polymers are well arranged molecularstructures. Further details on the piezoelectric polymer are providedbelow.

As noted above, piezoelectric electric generation, i.e., electricimpulses are not only generated by the piezoelectric polymer, but arealso generated by piezo nanocrystals that are present as one dispersedphase of the composite. Crystalline solids or crystals, e.g., the piezonanocrystals, have ordered structures and symmetry. The atoms,molecules, or ions in crystals are arranged in a particular manner;thus, have a long range order. In crystalline solids, there is aregular, repeating pattern; thus, we can identify a repeating unit.

In some embodiments, the piezo nanocrystal is provided by a ceramiccomposition. Ceramics exhibiting piezo-electric properties can belong tothe group of ferroelectric materials. One family of ceramic nanocrystalsexhibiting piezo-electric properties include lead zirconate titanate(PZT); in which the members of this family consist of mixed crystals oflead zirconate (PbZrO₃) and lead titanate (PbTiO₃). Piezo-ceramiccomponents have a polycrystalline structure comprising numerouscrystallites (domains) each of which consists of a plurality ofelementary cells. The elementary cells of these ferroelectric ceramicsexhibit the perovskite crystal structure, which can generally bedescribed by the structural formula A²⁺B⁴⁺O₃ ²⁻. The piezo nanocrystalsmay also include niobium (Nb) based crystals.

Similar to the piezoelectric polymer, the piezo electric nanocrystalsgenerate an electrical charge when mechanically loaded with pressure ortension, which is referred to above as the piezo effect. The piezonanocrystals are of a nanoscale. “Nanoscale” denotes that the piezonanocrystals have a cross-section width that is less than 500 nm. Insome examples, the piezo nanocrystals have a cross-sectional widthranging from 20 nm to 100 nm.

The piezo nanocrystals provide one dispersed phase of the composite, inwhich the matrix phase of the composite is provided by a piezo polymericmaterial. As used herein, the term “dispersed phase” denotes a secondphase (or phases) that is embedded in the matrix phase of the composite.The dispersed phase may be present throughout an entirety of thematerial that provides the matrix.

The composite also includes a second dispersed phase of carbonnanotubes. The carbon nanotubes provide pathways for distribution of theelectrical impulses to a surface of the composite impulse generatinglayer contacting the biological environment, and the delivery of freeradicals from the biological environment to at least the piezonanocrystals. “Nanotube” as used herein is meant to denote one form ofnanostructure having an aspect ratio of length to width greater than 10.The term “nanotube” includes single wall and multi-wall nanotubes unlessspecifically specified as distinct. In one embodiment, a carbon nanotubeis at least one graphene layer wrapped into a cylinder. In oneembodiment, a single wall carbon nanotube is a graphene rolled up into aseamless cylinder with diameter of the order of a nanometer. Amulti-wall carbon nanotube is a plurality of graphene sheets rolled upinto a seamless cylinder with diameter of the order of a nanometer.

The composite of the piezo polymer, the piezo nanocrystal and the carbonnanotubes can provide an interface structure for transmitting andreceiving electrical impulses from a biological environment. Forexample, the electric current produced by the composite may be utilizedby adjacent neurons to facilitate cell membrane depolarization andfurther propagation of the action potential along the neuronal/axonalnetwork. Compared to conventional neuronal tissue stimulatingtechnologies the operating power of devices employing the compositematerial of the piezo polymer, the piezo nanocrystal and the carbonnanotubes can be lower owing to enhanced biocompatibility and shape ofthe polymer electrode. Implantable devices built on the proposedtechnology can be suitable for clinical applications that include, butare not limited to, deep brain stimulation for neurogenerative diseases,e.g., Parkinson's disease; neuromodulation for major depression; urinaryincontinence; neuro-trauma; essential tremor; epilepsy; and combinationsthereof. The methods and structures of the present disclosure are nowdescribed with greater detail with reference to FIGS. 1-16.

FIG. 1 depicts one embodiment of a neuron-computer bi-directionalinterface structure 100 having a film and ribbon form factor, in whichthe interface structure is a multi-layered structure including acomposite layer 20 of a piezo polymeric matrix material 5, a firstdispersed phase of piezo nanocrystal material 10, and a second dispersedphase of carbon nanotubes 15, and at least one biological environmentinterface layer 25 having a grid geometry.

The composite layer 20 may be referred to a composite electrical impulsegenerating layer that includes a matrix phase of a piezo polymermaterial 5, a first dispersed phase of piezo nanocrystals 10, and seconddispersed phase of carbon nanotubes 15, in which the first and seconddispersed phases are presented throughout the matrix phase. Asillustrated in FIG. 1, the first dispersed phase of piezo nanocrystals10 and the second dispersed phase of the carbon nanotubes 15 may beuniformly distributed throughout the entirety of the matrix of the piezopolymer material 5. The composite electrical impulse generating layer 20is a flexible and stretchable piezoelectric generator that can provide aself-powered energy system for various applications.

The piezo polymer material 5 and piezo nanocrystal 10 convert mechanicalmotion into electrical impulses and accept electrons to charge thecomposite electrical impulse generating layer 20. In some embodiments,the addition of the first dispersed phase of the piezoelectricnano-material 10 in the form of nano-wires or nano-crystals into thematrix phase of the piezo polymer material 5 provides piezoelectriccomposition that can generate a high output power with higher efficiencywhen compared with other piezoelectric nanostructures. For example,nanowires of Pb(Mg_(1/3)Nb_(2/3))O₃—PbTiO₃ (PMN-PT) is one compositionof piezo nanocrystals 10 that can dispersed throughout a matrix of apiezo polymer material 5 that is β-phase polyvinylidene fluoridetrifluoroethylene (PVDF-TrFE), wherein the piezoelectric couplingcoefficient (d33) of PMN-PT nanowires is about 371 pm/V, which is over13 times higher than that of BaTiO₃ nanoparticles and 90 times higherthan that of NaNbO₃ nanowires, which are approximately 28 and 4 pm/V,respectively. It is noted that this example is intended to beillustrative only, and not intended to limit the present invention.Other compositions are equally suitable for the piezo polymer 5 and thepiezo nanocrystals 10.

For example, the piezo polymer 5 that provides the matrix for thecomposite may be polyvinylidene fluoride trifluoroethylene (PVDF-TrFE),which is a copolymer of PVDF. Polyvinylidene fluoride trifluoroethylene(PVDF-TrFE) can crystallize into β-phase directly from melt. In someembodiments, β-phase is thermodynamically favored for piezo-effect. Inother examples, the piezo polymer material may have a composition thatis selected from the group consisting of polyvinylidene flouride (PVDF),polyvinylidene fluoride (PVDF) copolymer with triflourethylene (TrFE),polyvinylidene fluoride (PVDF) copolymer with tetrafluorethylene (TFE),polyvinylidene fluoride (PVDF) copolymer with tetrafluorethylene (TFE)and triflourethylene (TrFE), nylon 11, poly(vinylidenecyanidevinylacetate), and combinations thereof.

In some embodiments, the piezo nanocrystal 10 can be composed of a piezoceramic material. For example, the piezo ceramic material that providesthe piezo nanocrystal 10 may have a composition selected from the groupconsisting of lead zirconate (PbZrO₃), lead titanate (PbTiO₃), andcombinations thereof.

In one example, the material composition of the piezo nanocrystal 10that is employed in the composite electrical impulse generating layer 20is a single-crystal piezoelectric (1-χ)PbZn_(1/3)Nb_(2/3)O₃-χPbTiO₃(PZNT) (further PMN-PT), which has a piezo-electric coupling coefficient(d33) up to 2500 pm/V, which is higher than that of conventionalpiezo-ceramics. For example, the piezoelectric coupling coefficient(d33) of single-crystal bulk PMN-PT is about 30 times higher than thatof BaTiO₃, which is approximately 85.3 pm/V, and almost 4 times higherthan that of PZT bulk material.

In another example, the material of the piezo nanocrystal 10 is Li-doped(K, Na)NbO₃ as a ceramic piezoelectric crystalline component. In yetanother example, which may be suitable for long-term biocompatibility,lead free materials may be preferred. For example, the piezo nanocrystal10 can be Ba(Ce_(x)Ti_(1-x)O₃), which is a mixture of Cerium-BariumTitanate (C-BT) with (0.94(Bi_(0.5)Na_(0.5)TiO₃)+0.06(BaTiO₃)) as asolid solution.

The first dispersed phase of piezo nanocrystals 10 may have ananowire-type geometry, and in some instances can have a substantiallyspherical geometry. In the instances, in which the piezo nanocrystals 10have a nanowire-type geometry, the piezo nanocrystals 10 have across-sectional width ranging from 20 nm to 100 nm, and the length ofthe piezo nanocrystals 10 can range from 100 nm to 500 nm. Thedimensions of the piezo nanocrystals 10 are provided for illustrativepurposes only, and are not intended to limit the present disclosure tothis example.

Still referring to FIG. 1, the composite electrical impulse generatinglayer 20 also includes a second dispersed phase of nanotubes, i.e.,carbon nanotubes 15. The carbon nanotubes 15 provide pathways fordistribution of the electrical impulses to a surface of the compositeimpulse generating layer contacting the biological environment. Thecarbon nanotubes 15 further provide for the delivery of the byproductsof the free radical degradation from the biological environment to bothpiezo-nanocrystals and piezo-polymer.

Carbon nanotubes (CNT) 15 are cylindrical structures made of carbon withunique mechanical and electronic properties. Carbon nanotubes (CNTs) 15are rolled up sheets of hexagonally ordered carbon atoms, giving tubeswith diameters on the order of a few nanometers and lengths typically inthe micrometer range. They may be single-walled or multiwalled (SWCNTsand MWCNTs respectively), and can be electrically conducting orsemiconducting depending upon the orientation of the carbon lattice withrespect to the tube axis (known as chirality in this context). In someembodiments, the carbon nanotubes (CNTs) 15 are designed to haphazardlypenetrate polymer matrix, i.e., piezo polymer material 5. The functionof the carbon nanotubes (CNTs) 15 are to collect, conduct, and acceptelectrons and toxic free oxygen radicals in intercellular space[O³⁻+C+e=CO₂], including those generated as a result of electricimpulses delivery.

In one embodiment, the carbon nanotubes 15 may have a high purity on theorder of about 95% to about 99% carbon. In an even further embodiment,the carbon nanotubes 15 have a high purity on the order of about 99% orgreater. In one embodiment, the carbon nanotubes 15 may be provided bylaser vaporization. In one embodiment, the single wall carbon nanotubes15 are formed using laser vaporization in combination with a catalyst,such as a metal catalyst. In one embodiment, the catalyst is supportedon a substrate, such as a graphite substrate, or the catalyst may befloating metal catalyst particles. In one embodiment, the metal catalystmay be composed of Fe, Ni, Co, Rh, Y or alloys and combinations thereof.

The carbon nanotubes 15 comprise a majority of carbon typically being ofhigh purity. In other examples, the carbon nanotubes include a carboncontent ranging from being greater than 50%, wherein a purificationprocess is utilized to provide carbon nanotubes having of high purity,such as greater than 90% carbon. In one embodiment, the carbon nanotubesmay be purified by a process that includes an acid treatment followed byan oxidation. In one embodiment, the acid treatment may includetreatment and oxidation steps are provided by a dilute HNO₃ reflux/airoxidation procedure.

Other methods of forming the carbon nanotubes may also be employed, suchas chemical vapor deposition (CVD). In another embodiment, the carbonnanotubes may be multi-walled.

The diameter of a single wall carbon nanotube 15 may range from about 1nanometer to about 400 nanometers. In another embodiment, the diameterof a single wall carbon nanotube 15 may range from about 1.2 nanometersto about 1.6 nanometers. In one embodiment, the nanotubes 15 used inaccordance with the present invention have an aspect ratio of length todiameter on the order of approximately 200:1 or greater. For example,the length of the carbon nanotubes (CNTs) 15 may be as great as 1 mm.

In some embodiments, the composite electrical impulse generating layer20 may include the piezo polymeric material 5 in an amount ranging from70 wt. % to 84.9 wt. %; piezo nanocrystals 10 in an amount ranging from15 wt. % to 30 wt. %; and carbon nanotubes 15 in an amount ranging from0.1 wt. % to 1 wt. %. In one example, the piezo polymeric material 5 ispresent in the composite electrical impulse generating layer 20 in anamount equal to 79.5 wt. %; the piezo crystal 10 are present in thecomposite electrical impulse generating layer 20 in an amount equal to20 wt. % and the carbon nanotubes 15 are present in an amount that isequal to 0.5 wt. %.

In some embodiments, the thickness of the composite impulse generatinglayer 20 may range from 40 μm to 300 μm. In one example, the thicknessof the composite impulse generating layer 20 is equal to 100 μm.

In one example, the composite impulse generating layer 20 may have apiezo-electric coefficient d33 ranging from 30-350 pC/N, and apolarization ranging from 2500-10000 mC/cm².

Referring to FIG. 1, the interface structure 100 may further include atleast one biological environment interface layer 25 is in contact withthe surface of the composite impulse generating layer 20 to provide amulti-layered interface structure, the electrical impulses reaching thesurface of the composite impulse generated layer 20 transmitted bybiological environmental interface layer to stimulate cells in thebiological environment. The biological environmental interface layer 25may also be referred to as an outer layer.

In some embodiments, the at least one biological environment interfacelayer 25 is for harvesting and the distribution of electrical impulses.In some examples, the at least one biological environment interfacelayer 25 may include a metal containing layer, which may be gold (Au).The at least one biological environment interface layer 25 is notlimited to gold (Au). For example, in some other embodiments, the atleast one biological environmental interface layer is provided by ametal composition selected from the group consisting of silver,platinum, iridium, and combinations thereof including combinations withgold. In some embodiments, the metal coating for providing thebiological environmental interface 25 can be provided by plating, e.g.,electroplating and/or electroless plating, physical vapor deposition(PVD), e.g., sputtering and/or chemical vapor deposition (CVD)technology.

In some embodiments, the biological environmental interface 25 is in aform of a perforated foil or a mesh. In the metal layer for thebiological environmental interface 25, the spaces are formed inpredetermined patterns that allow for the metal foil or mesh to flexwithout buckling. The metal between the spaces defines a plurality ofdiscrete electrodes on the metal foil when the foil is cut and formedinto a structure. This can allow for the creation and concentration ofelectrical impulses in certain points of the biological environmentalinterface 25. The metal layer for the biological environmental interface25 may have a thickness ranging from 8 μm to 12 μm. In one example, themetal layer for the biological environmental interface 25 may have athickness of 10 μm.

In other embodiments, the biological environmental interface 25 may beprovided metal nano-particles embedded in the polymer, e.g. mixture ofpiezo-polymer and dielectric polymers; and/or a random distribution ofnano metal dots and/or micro metal dots on the surface of thefilm/ribbon geometry form factor for the interface structure 100.

In some other embodiments, the biological environmental interface layer25 may also be provided by a mixture of piezo polymeric material anddielectric polymeric material. The piezo polymeric material of thebiological environmental interface layer 25 may be similar incomposition to the piezo polymer 5 of the composite electrical impulsegenerating layer 20. For example, the piezo polymer for the biologicalenvironmental interface layer 25 may be polyvinylidene fluoridetrifluoroethylene (PVDF-TrFE). In some embodiments, the piezo polymermaterial may be mixed with a dielectric polymer, such aspolydimethylsiloxane (PDMS). For example, the mixture of piezo polymerand dielectric polymer for providing a biological environmentalinterface layer 25 may include 10 wt. % to 30 wt. % piezo polymer, and70 wt. % to 90 wt. % dielectric polymer. In some instances the mixtureof piezo polymer and dielectric polymer for the biological interfacelayer 25 may also include a dispersed phase of carbon nanotubes. In oneembodiment, the carbon nanotubes may be present in the piezo polymer anddielectric polymer composition in an amount ranging from 5 wt. % to 20wt. %.

In some embodiments, the biological environmental interface 25 may beomitted from the structure depicted in FIG. 1. In some otherembodiments, the interface structure 100 that is depicted in FIG. 1 mayinclude two biological environmental interfaces 25, which would includea first biological environmental interface 25, as depicted in FIG. 1,and a second biological environmental interface (not depicted) on theopposing side of the composite electrical impulse generating layer 20from the first biological environmental interface 25.

Still referring to the interface structure 100 that is depicted in FIG.1, the composite electrical impulse generating layer 20 harvestsmechanical energy in a form of minute omni-directional accelerations anddecelerations, to transform this energy into electric impulses viapiezo-electric effect in the crystals, i.e., nanocrystals 10, and thepiezo-polymer 5. These impulses will be further distributed to the goldsurface, i.e, the biological environmental interface 25, by the carbonnanotubes (CNTs) 15. Further, this composite electrical impulsegenerating layer 20 is expected to be sensitive to changes in themembrane depolarization of juxtapositioned neurons. The neuronalmembrane depolarization is expected to transform into a mechanicalstress of the layer. Thus, this composite material represents abidirectional interface with an excitable tissue, e.g., a neuronalnetwork in the brain and/or spinal cord. In some embodiments, thepresence of CNTs 15 warrant electrons to go to the surface of thematerial, allowing a gradient for negative ions and negatively chargedfree radicals to enter the depth of the material via CNT, and distributeelectrons within piezo-polymer and amongst piezo-crystals. For instance,free radical oxygen species, e.g. H₂O₂, O₃ ⁻ etc) will enter thecomposite impulse generated layer 20 and transform into H₂O and CO₂ (orHCO₃— (carbonate buffer).

It is noted that the form factor, number of type of material layers andmaterial compositions for the material layers that are provided in FIG.1 are only one example of an interface structure 100 that may beprovided by the present disclosure.

FIG. 2 depicts another embodiment of a neuron-computer bi-directionalinterface structure having a film and ribbon form factor, in which theinterface structure 100 a is a multi-layered structure including acomposite electrical impulse generating layer 20; a composite electricalimpulse amplifying layer 21, and at least one biological environmentinterface layer 25 having a grid geometry. Some aspects of the interfacestructure 100 a depicted in FIG. 2 are similar to the interfacestructure 100 that is depicted in FIG. 1. For example, the descriptionof the composite electrical impulse generating layer 20 and thebiological environment interface layer 25 for the interface structure100 that is depicted in FIG. 1 can provide a description for at leastsome examples of the composite impulse generating layer 20 and thebiological environment interface layer 25 that is depicted in FIG. 2.

The composite electrical impulse amplifying layer 21 is present betweenthe composite impulse generating layer 20 and the biological environmentinterface layer 25. The composite electrical impulse amplifying layer 21is similar in its composition to the composite impulse generating layer20. For example, similar to the composite impulse generating layer 20,the composite impulse amplifying layer 21 may include a matrix phase ofa piezo polymer material 5, a first dispersed phase of piezonanocrystals 10, and second dispersed phase of carbon nanotubes 15, inwhich the first and second dispersed phase presented through the matrixphase. However, the concentration of piezo nanocrystals 10 in thecomposite electrical impulse amplifying layer 21 is higher than theconcentration of the piezo nanocrystals 10 in the composite electricalimpulse generating layer 10. In one embodiment, the composite impulseamplifying layer 21 may include the piezo polymer 5 in an amount rangingfrom 10 wt. % to 30 wt. %; the piezo nanocrystals 10 may be present inan amount ranging from 70 wt. % to 89.9 wt. %; and carbon nanotubes(CNTs) in an amount ranging from 0.1 wt. % to 1.0 wt. %. In one example,the composite impulse amplifying layer 21 can include the piezo polymermaterial 5 in an amount equal to 24.5 wt. %, the nano crystals 10 in anamount equal to 70 wt. %, and the carbon nanotubes 15 may be present inan amount equal to 0.5 wt. %. For the purposes of comparison, thecomposite electrical impulse generating layer 20 may include the piezopolymeric material 5 in an amount ranging from 70 wt. % to 84.9 wt. %;piezo nanocrystals 10 in an amount ranging from 15 wt. % to 30 wt. %;and carbon nanotubes 15 in an amount ranging from 0.1 wt. % to 1 wt. %.

Further, the composite impulse amplifying layer 21 has a higherpiezoelectric coefficient than the composite impulse generating layer20. In some embodiments, the piezo-electric coefficient d33 of thecomposite impulse amplifying layer 21 can range from 50-500 pC/N; andthe composite impulse amplifying layer 21 can have a polarizationranging from 3500-10000 mC/cm².

In some embodiments, the composite impulse amplifying layer 21 functionsto receive electrical impulses from the composite impulse generatinglayer 20 and increases the magnitude/charge/of the electrical impulses.The composite impulse amplifying layer 21 also functions to transmit theelectrical impulses to the biological environmental interface layer 25.It is noted that the composite impulse amplifying layer 21 alsogenerates electrical impulses.

The thickness of the composite impulse amplifying layer 21 may rangefrom 50 μm to 400 μm. In one example, the thickness of the compositeimpulse amplifying layer 21 is equal to 200 μm.

As noted above, with the exception of the difference in theconcentration of the piezo nanocrystals 10, the composite impulseamplifying layer 21 and the composite impulse generating layer 20 aresimilar. Therefore, the examples in the descriptions of the piezopolymeric materials 5, the piezo nanocrystals 10, and the carbonnanotubes 15 provided above for the composite impulse generating layer20 can provide examples for the piezo polymeric materials 5, the piezonanocrystals 10, and the carbon nanotubes 15 that are present in thecomposite impulse amplifying layer 21. It is not necessary that thecomponents, i.e., piezo polymeric material 4, piezo nanocrystals 10, andcarbon nanotubes (CNTs), have the same compositions for both thecomposite impulse generating layer 20 and the composite impulseamplifying layer 21.

Still referring to FIG. 2, the composite electrical impulse generatinglayer 20 harvests mechanical energy in a form of minute omni-directionalaccelerations and decelerations, to transform this energy into electricimpulses via piezo-electric effect in crystals and the piezo-polymeritself. These impulses will be further accepted by the compositeelectrical impulse amplifying layer 21, which will amplify theseimpulses due to the higher piezo-electric coefficient. These amplifiedimpulses will be further distributed back to the gold surface, i.e., thebiological environmental interface layer 25, via the carbon nanotubes(CNTs) 15.

This material is expected to be sensitive to changes in the membranedepolarization of juxtapositioned neurons. The neuronal membranedepolarization is expected to transform into a mechanical stress of thecomposite electrical impulse generating layer 20. This mechanical stressof the highly flexible composite electrical impulse generating layer 20is transformed in the (with composite electrical impulse amplifyinglayer 21 (having a higher piezo-electric coefficient) into amplifiedelectrical impulses. Thus, the composite material of the interfacestructure 100 a depicted in FIG. 2 represents another embodiment of abidirectional interface with an excitable tissue (neuronal network inthe brain and/or spinal cord).

In some embodiments, the biological environmental interface 25 may beomitted from the structure depicted in FIG. 2. In some otherembodiments, the interface structure 100 that is depicted in FIG. 1 mayinclude two biological environmental interfaces 25, which would includea first biological environmental interface 25 in direct contact with thecomposite electrical impulse amplifying layer 21, as depicted in FIG. 2,and a second biological environmental interface (not depicted) on theopposing side of the interface structure 100 a, e.g., on the exposedopposite face of the composite electrical impulse generating layer 20.

FIG. 3 depicts another embodiment of an interface structure 100 c. Inthe embodiment that is depicted in FIG. 3, the interface structure 100 cincludes a composite electrical impulse amplifying layer 21 as the coreof a interface structure 100 c having a film/ribbon form factor, inwhich the composite electrical impulse amplifying layer 21 is presentbetween two layers of composite electrical impulse generating layers 21.The composite electrical impulse generating layer 20 and the compositeelectrical impulse amplifying layer 21 that is depicted in FIG. 3 hasbeen described above with reference to the embodiments depicted in FIGS.1 and 2.

The interface structure 100 c that is depicted in FIG. 3, includes acrystalline saturated layer provided by the composite electric impulseamplifying layer 21 that is situated between polymer saturated layersprovided by the composite electric impulse generating layers 20 toprovide a cascade amplifier of the direct piezoelectric effect. Thecascade amplifier is produced by a stress-dependent change inpolarization, which can be increased as result of the high flexibilityand durability of the electric impulse generating materials, which alsofollow to improve a measurable potential difference across the material.

Referring to FIG. 3, in some embodiments, the bottom compositeelectrical impulse generating layer 20 (as orientated on in FIG. 3) isexpected to harvest mechanical energy in a form of minuteomni-directional accelerations and decelerations, to transform thisenergy into electric impulses via piezo-electric effect in the crystalsand the piezo-polymer itself. The impulses are accepted by the centrallypositioned composite electrical impulse amplifying layer 21, whichamplifies these impulses due to the higher piezo-electric coefficient ofthe composite electrical impulse amplifying layer 21 when compared tothe composite electrical impulse generating layer 20. Then electricalimpulse from the centrally positioned composite electrical impulseamplifying layer 21 can then be applied to the top composite electricalimpulse generating layer 20 (as orientated in FIG. 3). Following theapplication of electric charge the inverse/secondary piezoelectriceffect, which is a deformation of the material, occurs. In the materialthat underwent poling such deformations lead to the compressive stressalong the electro-magnetic field lines. This mechanical stress of thehighly flexible layer top composite electrical impulse generating layer20 is transformed in the composite electrical impulse amplifying layer21 (with higher piezo-electric coefficient) into amplified electricalimpulse. This effect is an example of a piezoelectric cascade amplifierand these amplified impulses will be further distributed back to thebiological environmental interface 25 (which can be provided by a goldgrid) via the carbon nanotubes 15.

The piezoelectric composite materials of the interface structure 100 cdepicted in FIG. 3 display coupled structural deformation in amplifiermodes for such as in a shear or bend type structural deformation, wherea shear deformation of the embedded piezoelectric material produces alargely bending deformation of the composite structure.

The composite material depicted in FIG. 3 represents a bidirectionalinterface with an excitable tissue, which can be suitable forinteraction with a neuronal network in the brain and/or spinal cord.

In some embodiments, one or both of the biological environmentalinterfaces 25 may be omitted from the structure depicted in FIG. 3.

FIG. 4 illustrates another example of an interface structure 100 chaving a film and ribbon form factor, in which the interface structure100 c is a multilayered stack including a composite electrical impulsegenerating layer 20, a composite electrical impulse amplifying layer 21,a piezoelectric composite layer free of carbon nanotubes 22, a resinlayer 23 and a biological environmental interface layer 25. Thepiezoelectric composite layer that is free of carbon nanotubes 22 andthe resin layer 23 may be present as a bilayer positioned between thebiological environmental interface layer 25 and the composite impulseamplifying layer 21 so that the resin layer 23 is in contact with thebiological environmental interface layer 25 and the piezoelectriccomposite layer free of carbon nanotubes 22 is in contact with thecomposite impulse amplifying layer 21.

The composite electrical impulse generating layer 20 and the compositeelectrical impulse amplifying layer 21 have been described above withreference to FIGS. 1-3. The piezoelectric composite layer free of carbonnanotubes 22 includes a matrix of a piezo polymeric material 5 and adispersed phase of a piezo nanocrystals 10. The piezo polymeric material5 and the piezo nanocrystal material 10 that is employed in thepiezoelectric composite layer that is free of carbon nanotubes 22 issimilar to the piezo polymeric material 5 and piezo nanocrystal material10 that is employed in the composite electrical impulse generating layer20 and the composite electrical impulse amplifying layer 21.

In one embodiment, the piezoelectric composite layer that is free ofcarbon nanotubes 22 includes a piezo polymeric material 5 in an amountranging from 10 wt. % to 30 wt. %, and the nanocrystals 10 are presentin an amount ranging from 70 wt. % to 90 wt. %. In one example, thepiezo electric composite layer that is free of carbon nanotubes 22includes a piezo polymeric material 5 in an amount equal to 20 wt. %,and piezo nanocrystals in an amount equal to 80 wt. %. The thickness ofthe piezo composite layer that is free of carbon nanotubes 22 may rangefrom 50 μm to 400 μm. In one example, the thickness of the piezocomposite layer that is free of carbon nanotubes 22 may be equal to 200microns

In some embodiments, the piezo-electric coefficient d33 of the piezocomposite layer that is free of carbon nanotubes 22 can range from40-500 pC/N; and the piezo composite layer that is free of carbonnanotubes 22 can have a polarization ranging from 3100-10000 mC/cm².

The piezo composite layer that is free of carbon nanotubes 22 can be forgeneration and amplification of the signal due to the high piezo-crystalcontent of the layer. In some embodiments, the piezo composite layerthat is free of carbon nanotubes 22 may function in a manner similar tothe composite electrical impulse amplifying layer 21, but without theincorporation of carbon nanotubes.

The resin layer 23 may be composed of a polymer, such as sulfonated polyether ether ketone (SPEEK) incorporated with micron-sized sulfonatestyrene-crosslinked divinyl benzene-based cation exchange resinparticles. The thickness of the resin layer 23 may range from 50 μm to200 μm. In some examples, the resin layer 23 may provide forpotassium-sodium (K-Na) ion exchange. The resin layer 23 is anion-exchange material.

It is noted that the bilayer of the piezo composite layer that is freeof carbon nanotubes 22 and the resin layer 23 is not limited to onlybeing incorporated into an interface structure as depicted in FIG. 4.For example, another embodiment of an interface structure is depicted inFIG. 5 having form factor in the geometry of a film/ribbon, and amultilayered stack including a first biological environmental interfacelayer 25 (at the bottom of the stack), a first resin layer 23, a firstpiezoelectric composite layer free of carbon nanotubes 22, a firstcomposite electrical impulse amplifying layer 21, a composite electricalimpulse generating layer 20, a second composite electrical impulseamplifying layer 21, a second piezoelectric composite layer free ofcarbon nanotubes 22, a second resin layer 23 and a second biologicalenvironmental interface layer 25. Each of these layers have beendescribed above for structures having similar reference numbers.Further, one or both of the first and second biological environmentalinterface layer 25 may be omitted from the structures depicted in FIGS.4 and 5.

FIG. 6 depicts a neuron-computer bi-directional interface structurehaving a film and ribbon form factor, in which the interface structureis a multi-layered structure including a composite layer of a piezopolymeric matrix material 5, a first dispersed phase of piezonanocrystal material 10, and a second dispersed phase of carbonnanotubes 15, a dielectric polymer layer 30, and at least one biologicalenvironment interface layer 25 having a grid geometry. The dielectricpolymer layers employed in the interface structure 100 e depicted inFIG. 6 may be composed of bio-compatible materials with high dielectricproperties.

The dielectric polymer layer 30 can provide an isolating surface of theinterface structure 100 e that is depicted in FIG. 6. The dielectricpolymer layer 30 may be composed of polydimethylsiloxane (PDMS). ThePDMS empirical formula is (C₂H₆OSi)_(n) and its fragmented formula isCH₃[Si(CH₃)₂O]_(n)Si(CH₃)₃, n being the number of monomers repetitions.Depending on the size of monomers chain, the non-cross-linked PDMS maybe almost liquid (low n) or semi-solid (high n). The siloxane bondsresult in a flexible polymer chain with a high level of viscoelasticity.

It is noted that PDMS is only one example of a dielectric polymer layer30 that can be employed in an interface structure 100 e for aneuron-computer bi-directional interface structure. For example, otherdielectric polymer compositions may be provided by other mineral-organicpolymer (a structure containing carbon and silicon) of the siloxanefamily. The dielectric polymer layer 30 may have a thickness rangingfrom 40 μm to 300 μm. In one example, the dielectric polymer layer 30has a thickness of 100 μm.

The at least one biological environment interface layer 25 of theinterface structure 100 e depicted in FIG. 6 may be omitted.

FIG. 7 depicts another embodiment of an interface structure 100 fincluding the dielectric polymer layer 30 that is described above withreference to FIG. 6. FIG. 7 depicts one embodiment of a neuron-computerbi-directional interface structure having a film and ribbon form factor,in which the interface structure 100 f is a multi-layered structureincluding a dielectric polymer layer 30 positioned between two compositeelectrical impulse generating layers 20; and at least one biologicalenvironmental interface layer 25 having a grid geometry. Morespecifically, the interface structure 100 f depicted in FIG. 7 includesto biological environmental interface layers 25 on opposing sides of theinterface structure 100 f. In some embodiments, one or both of thebiological environmental interfaces 25 may be omitted from the structuredepicted in FIG. 3.

In some embodiments, the aforementioned dielectric polymer composition,i.e., the dielectric composition for the dielectric polymer layer 30,can provide the matrix of a composite including piezo nanocrystals 10and carbon nanotubes 15. The piezo nanocrystals 10 and carbon nanotubes15 have been described above. The composite layer having the matrix ofthe dielectric polymer layer and dispersed phases of piezo electricmaterials, i.e., the piezo nanocrystals, and carbon nanotubes, thematerial layer may be referred to as a dielectric matrix composite withdispersed phases of piezo nanocrystals 10 and carbon nanotubes 15. Inone example, the dielectric matrix composite with dispersed phases ofpiezo nanocrystals 10 and carbon nanotubes 15 includes the dielectricpolymer, e.g., polydimethylsiloxane (PDMS), in an amount ranging from 70wt. % to 84.9 wt. %, the piezo nanocrystals 10 in an amount ranging from15 wt. % to 30 wt. % and the carbon nanotubes 0.1 wt. % to 1.0 wt. %. Inone example, the dielectric matrix composite with dispersed phases ofpiezo nanocrystals 10 and carbon nanotubes 15 includes the dielectricpolymer, e.g., polydimethylsiloxane (PDMS), present in an amount equalto 79.5 wt. %, the piezo nanocrystals 10 present is an amount equal to20 wt. % and the carbon nanotubes 0.5 wt. %.

In one embodiment, the piezo-electric coefficient d33 of the dielectricmatrix composite with dispersed phases of piezo nanocrystals 10 andcarbon nanotubes 15 can range from 0.5-2 pC/N; and the piezo compositelayer that is free of carbon nanotubes 22 can have a polarizationranging from 2500-3000 mC/cm².

In one example, the dielectric matrix composite with dispersed phases ofpiezo nanocrystals and carbon nanotubes may be incorporated into aninterface structure having a film/ribbon form factor. For example, thedielectric matrix composite with dispersed phases of piezo nanocrystalsand carbon nanotubes may be incorporated into an interface structure, asdepicted in FIG. 6, in which the dielectric matrix composite withdispersed phases of piezo nanocrystals and carbon nanotubes issubstituted for the dielectric polymer layer 30. In this embodiment, acomposite electrical impulse generating layer 20 is present atop thedielectric matrix composite with dispersed phases of piezo nanocrystalsand carbon nanotubes, and a biological environment interface layer 25 ispresent atop the composite electrical impulse generating layer 20. Inthis example, the dielectric matrix composite with dispersed phases ofpiezo nanocrystals and carbon nanotubes may have a thickness rangingfrom 40 μm to 300 μm. In one example, the dielectric matrix compositewith dispersed phases of piezo nanocrystals and carbon nanotubes has athickness of 100 μm.

In another example, the dielectric matrix composite with dispersedphases of piezo nanocrystals and carbon nanotubes may be incorporatedinto an interface structure, as depicted in FIG. 7, in which thedielectric matrix composite with dispersed phases of piezo nanocrystalsand carbon nanotubes is substituted for the dielectric polymer layer 30that is present between two composite electrical impulse generatinglayers 20.

FIGS. 1-7 illustrate only some examples of interface structures having afilm/ribbon form factor. In other examples, an interface structure isprovided that includes at least a bilayer of the piezo composite layerthat is free of carbon nanotubes, and a layer provided by a mixture ofpiezo polymeric material and dielectric polymeric material.

The piezo composite layer that is free of carbon nanotubes for thebilayer is similar to the layer identified by reference number 22 inFIGS. 4 and 5).

For the layer provided by a mixture of piezo polymeric material anddielectric polymeric material, the piezo polymeric material may besimilar in composition to the piezo polymer 5 of the compositeelectrical impulse generating layer 20. For example, the piezo polymerfor the biological environmental interface layer 25 may bepolyvinylidene fluoride trifluoroethylene (PVDF-TrFE). In someembodiments, the piezo polymer material may be mixed with a dielectricpolymer, such as polydimethylsiloxane (PDMS). For example, the layerprovided by the mixture of piezo polymer and dielectric polymer mayinclude 70 wt. % to 90 wt. % piezo polymer, and 10 wt. % to 30 wt. %dielectric polymer. The layer provided by the mixture of the piezopolymer material may be characterized by a piezo-electric coefficientd33 ranging from 10-100 pC/N;—and a polarization ranging from 1500-5000mC/cm².

The interface structure including the bilayer of the piezo compositelayer that is free of carbon nanotubes, and a layer provided by amixture of piezo polymeric material and dielectric polymeric materialmay further include at least one biological interface layer (alsoreferred to as outer layer) also composed of a polymeric materialincluding a dispersed phase of carbon nanotubes. The carbon nanotubesmay be present in an amount ranging from 5 wt. % to 20 wt. %.

In yet another example, the interface structure may include a stack of alayer provided by a mixture of piezo polymeric material and dielectricpolymeric material that is positioned between two piezo composite layersthat are free of carbon nanotubes.

The piezo composite layer that is free of carbon nanotubes is similar tothe layer identified by reference number 22 in FIGS. 4 and 5.

The layer provided by the mixture of the piezo polymer material anddielectric material layer has been described above in the description ofthe bilayer of the piezo composite layer that is free of carbonnanotubes and the mixture of the piezo polymer material and dielectricmaterial layer provides one example of the composition of the mixture ofthe piezo polymer material and dielectric material layer that ispositioned between two piezo composite layers that are free of carbonnanotubes. In another embodiment, the mixture of the piezo polymermaterial and dielectric material layer includes 10 wt. % to 30 wt. %piezo polymer, and 70 wt. % to 90 wt. % dielectric polymer. The layerprovided by this mixture may be characterized by a piezo-electriccoefficient d33 ranging from 0.5-2 pC/N

The interface structure including the stack of a layer provided by amixture of piezo polymeric material and dielectric polymeric materialthat is positioned between two piezo composite layers that are free ofcarbon nanotubes may further include at least one biological interfacelayer (also referred to as outer layer) also composed of a polymericmaterial including a dispersed phase of carbon nanotubes. The carbonnanotubes may be present in an amount ranging from 5 wt. % to 20 wt. %.

It is noted that in one embodiment the film and ribbon form factordepicted in FIGS. 1-7, which is substantially a 2D geometry, may bemanipulated to provide the geometry of a haphazard ribbon, as depictedin FIG. 8. In another embodiment, the film and ribbon form factordepicted in FIGS. 1-7, may be manipulated to provide the geometry of amobious loop, as depicted in FIG. 9. In yet another embodiment, the filmand ribbon form factor depicted in FIGS. 1-7, may be manipulated toprovide the geometry of a coil, i.e., a rolled up matt, as depicted inFIG. 10.

The form factors depicted in FIGS. 1-10 may have exterior dimensions ona microscale, in which the greatest dimension, e.g., length of the formfactor may range from 100-200 micrometers.

In another embodiment, an ultra-stretchable elastic-composite generatoris provided by employing Ecoflex silicone rubber-based piezoelectriccomposites and long silver nanowire-based stretchable electrodes.

It is noted that the interface structures provided herein are notlimited to the two dimensional film and ribbon form factors describedwith reference to FIGS. 1-7. In some embodiments, the form factor forthe interface material 100 g, 100 h, 100I, 100 k may be a threedimensional (3D) geometry, such as a sphere having columns/spikesextending from the surface of the sphere, a sphere withoutcolumns/spikes, a sponge, a dendritic structure, or a wire geometrystructure, as depicted in FIGS. 11-16. The three dimensional formfactors that are depicted in FIGS. 11-16 may have exterior dimensions inthe mircoscale, e.g., having dimensions ranging from 100 μm to 200 μm.Further, some of the following form factors described with reference toFIGS. 11-16 maybe introduced to a living tissue in the form of aninjectable suspension of said structures.

FIG. 11 is a neuron-computer bi-directional interface structure having athree dimensional form factor in the shape of a sphere having aplurality of spikes/columns extending from the outer surface of thesphere. The interface structure 100 g depicted in FIG. 11 includes anucleus 35 of a composite electrical impulse generating material thatincludes a piezo polymeric matrix with a first dispersed phase of apiezo nanocrystals and a second dispersed phase of carbon nanotubes. Thematerial that provides the nucleus of the 35 is similar to the compositeelectrical impulse generating material 20 that is described above withreference to FIGS. 1-7 and the composite electrical impulse amplifyingmaterial 21 that is described above with reference to FIGS. 2-5.Therefore, the description of the compositions for the piezo polymermatrix 5, the piezo nanocrystals 10 and the carbon nanotubes 15 for thecomposite electrical impulse generating material 20 is suitable for thedescription of the piezo polymer matrix and the dispersed phases of thepiezo nanocrystals and the carbon nanotubes for the nucleus of thesphere having the plurality of spikes/columns that is depicted in FIG.11.

In some embodiments, the piezo polymer matrix is present in the nucleus35 in an amount ranging from 10 wt. % to 30 wt. %, the piezonanocrystals are present in the nucleus 35 in an amount ranging from 70wt. % to 95 wt. %, and the carbon nanotubes are present in the nucleus35 in an amount ranging from 5 wt. % to 30 wt. %. In one example, thenucleus 35 includes a piezo polymeric matrix in an amount equal to 20wt. %, piezo nanocrystals in an amount equal to 70 wt. %, and the carbonnanotubes are present in an amount equal to 10 wt. %. The nucleus 35 mayhave a diameter ranging from 100 μm to 1000 μm. In one example, thenucleus 35 has a diameter that is equal to 500 μm.

The outer sphere 40 of the sphere structure depicted in FIG. 11 may becomposed of composite material of a piezo polymeric material and piezonanocrystals. The outer sphere 40 is composed of material that issimilar to the piezoelectric composite layer free of carbon nanotubes 22that is described above with reference to FIGS. 4 and 5.

Therefore, the description of the compositions for the piezo polymermatrix 5, and the piezo nanocrystals 10 for the piezoelectric compositelayer free of carbon nanotubes 22 is suitable for the description of thepiezo polymer matrix and the dispersed phases of the piezo nanocrystalsfor the outer sphere 40 of the sphere having the plurality ofspikes/columns that is depicted in FIG. 11.

In some embodiments, the piezo polymer matrix is present in the outersurface 40 in an amount ranging from 70 wt. % to 90 wt. %, and the piezonanocrystals are present in the outer surface 40 in an amount rangingfrom 10 wt. % to 30 wt. %. In one example, the outer sphere 40 includesa piezo polymeric matrix in an amount equal to 80 wt. %, and the piezonanocrystals are present in an amount equal to 20 wt. %. The outersphere 40 may have a thickness (measured from the surface of the core 35to the outer surface of the outer sphere 40) ranging from 500 μm to 5000μm. In one example, the outer sphere 40 has a thickness that is equal to2000 μm.

Still referring to FIG. 11, the plurality of spikes/columns 45 extendingfrom the outer surface of the sphere 40 may be composed of a majority ofcarbon nanotubes and piezo polymeric material. The carbon nanotubes andthe piezo polymeric material employed in the spikes/columns 45 have beendescribed above with reference to FIGS. 1-7. In one embodiment, thecarbon nanotubes may be present in the spikes columns 45 in an amountranging from 70 wt. % to 95 wt. %, and the piezo polymeric material maybe present in an amount ranging from 5 wt. % to 30 wt. %.

The spikes/columns 45 have physical dimensions of a diameter on theorder of 2 μm; an overall length on the order of 2000 μm (measuredextending from the surface of the nucleus 35 to the tip of thespikes/columns 45 extending from the outer sphere 40), and a protrusiondistance equal to 1 μm (measured from the surface of the outer sphere40).

Still referring to FIG. 11, the outer surface of the sphere having aplurality of spikes/columns may have an electrically conductive layerpresent thereon, which can provide an biological environment interfacelayer. It is noted that any of the compositions described above for thebiological environment interface layer 25 may provide this layer for thestructure depicted in FIG. 11. For example, the outer surface of thesphere may include a gold layer having thickness ranging from 8 micronsto 12 microns, and in one example being equal to 10 microns.

FIG. 12 depicts another embodiment of a neuron-computer bi-directionalinterface structure having a three dimensional form factor in the shapeof a sphere having a nucleus 36 present within an outer sphere 41. Inthe embodiment that is depicted in FIG. 12 both the nucleus 36 and theouter sphere 41 are composed of composite materials including a piezopolymeric matrix, a first dispersed phase of piezo nanocrystals and asecond dispersed phase of carbon nanotubes (CNTs). The nucleus 36 may becomposed of composite composition that is similar to the compositeelectrical impulse amplifying layer 21 that is described above withreference to FIGS. 2-5. In some embodiments, the piezo polymer matrix ispresent in the nucleus 36 in an amount ranging from 10 wt. % to 30 wt.%, the piezo nanocrystals are present in the nucleus 36 in an amountranging from 70 wt. % to 95 wt. %, and the carbon nanotubes are presentin the nucleus 36 in an amount ranging from 5 wt. % to 20 wt. %. In oneexample, the nucleus 36 includes a piezo polymeric matrix in an amountequal to 20 wt. %, piezo nanocrystals in an amount equal to 70 wt. %,and the carbon nanotubes are present in an amount equal to 10 wt. %. Thenucleus 36 may have a diameter ranging from 100 μm to 1000 μm. In oneexample, the nucleus 36 has a diameter that is equal to 500 μm.

The outer sphere 41 of the sphere structure depicted in FIG. 12 may becomposed of composite material of a piezo polymeric material, piezonanocrystals and carbon nanotubes. The outer sphere 41 is composed ofmaterial that is similar to the composite electrical impulse generatinglayer 20 that is described above with reference to FIGS. 1-7. In someembodiments, the piezo polymer matrix is present in the outer sphere 41in an amount ranging from 70 wt. % to 95 wt. %, the piezo nanocrystalsare present in the outer sphere 41 in an amount ranging from 15 wt. % to30 wt. %, and the carbon nanotubes are present in an amount ranging from5 wt. % to 20 wt. %. In one example, the outer sphere 41 includes apiezo polymeric matrix in an amount equal to 70 wt. %, the piezonanocrystals are present in an amount equal to 20 wt. %, and the carbonnanotubes are present in an amount equal to 10 wt. %. The outer sphere41 may have a thickness (measured from the surface of the core 35 to theouter surface of the outer sphere 41) ranging from 500 μm to 5000 μm. Inone example, the outer sphere 41 has a thickness that is equal to 2000μm.

Still referring to FIG. 12, the outer surface of the sphere may have anelectrically conductive layer present thereon, which can provide anbiological environment interface layer. It is noted that any of thecompositions described above for the biological environment interfacelayer 25 may provide this layer for the structure depicted in FIG. 12.For example, the outer surface of the sphere may include a gold layerhaving thickness ranging from 8 microns to 12 microns, and in oneexample being equal to 10 microns.

FIG. 13 depicts a neuron-computer bi-directional interface structurehaving a three dimensional form factor in the shape of a sponge(identified as interface structure 100 i). FIG. 14 depicts aneuron-computer bi-directional interface structure having a threedimensional form factor in the three dimensional blot (identified asinterface structure 100 g). In some instances, the three dimensionalblot interface structure 100 g may be referred to as a dendriticgeometry. The dendritic geometry can results from the application of aninjectable “electrode” in the form of a suspension that polymerizes inthe neuron-glial meshwork in situ. In this example, the nano-particlesof the piezo-material are to be suspended in the liquid biocompatiblepolymer composition that promptly polymerizes in the targeted area inthe “dendrite-like” distributed fashion. Such “distributeddendrite-like” electrode will provide an intimate functionalbi-directional interface with the cellular membranes. The currentlyavailable metal point electrodes are lacking these features.

In one embodiment, the material that provides the sponge and threedimensional blot interface structures 100 i, 100 g may be a composite ofpiezoelectric materials and carbon nanotubes. In one example, thecomposite material that provides the sponge and three dimensional blotinterface structures 100 i, 100 g can include a piezo polymeric materialin an amount ranging from 70 wt. % to 95 wt., piezo nanocrystals in anamount ranging from 15 wt. % to 30 wt. % and carbon nanotubes present inan amount ranging from 0.1 wt. % to 1 wt. %. The composite materialemployed in the interface structures 100 i, 100 g is similar to thecomposite electrical impulse generating layer 20 and the compositeelectrical impulse amplifying layer 21. Therefore, the description ofthe compositions for the piezo polymer matrix 5, the piezo nanocrystals10 and the carbon nanotubes 15 for the composite electrical impulsegenerating layer 20 and the composite electrical impulse amplifyinglayer 21 is suitable for providing at least one example for thesematerials applied to the interface structures 100 i, 100 j depicted inFIGS. 13 and 14. For example, the piezo polymeric material 5 may bepolyvinylidene fluoride trifluoroethylene (PVDF-TrFE).

In another embodiment, the composition of a piezo polymeric materialsuch as polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) for theinterface structures 100 i, 100 j depicted in FIGS. 13 and 14 may besubstituted with a polymeric material selected for enhancedbiocompatibility, such as polyanhydridepoly-[bis(p-carboxyphenoxy)propane-sebacic acid] copolymer (PCPP-SA). Insome embodiments, the sponge and three dimensional blot interfacestructures 100 i, 100 g may be porous structures having a pore diameterranging from 5 μm to 20 μm.

The three dimensional blot interface structure 100 g having dendriticgeometry may be injected into tissue and formed therein from a liquidpolymer with suspended piezo-electric nano-crystals. Once injected intissue (approximate volume 3-5 cubic mm) the material promptlypolymerizes, so the suspended nano-crystals become embedded in (semi-)rigid polymer matrix. The embedded nano-generators will be positioned inthe immediate proximity of the membranes of the excitable elements ofthe brain, i.e. neurons (soma, axons, and dendrites) as well as of glialcells. We anticipate that these excitable cells will amplify andpropagate impulses according to their physiologic projections.

FIGS. 15 and 16 depict some embodiments of a neuron-computerbi-directional interface structure having a three dimensional formfactor having a wire type geometry. The wire type geometry may includean inner core 50 and an outer layer 55 that are each comprised ofelectrical impulse generating composites including a piezo polymericmaterial, piezo nanocrystals and carbon nanotubes. The inner core 50 mayhave a higher concentration of piezo nanocrystals than the outer layer55. For example, the inner core 50 may be composed of 70 wt. % to 95 wt.% piezo nanocrystals and the outer layer 55 may be composed 15 wt. % to30 wt. % piezo nanocrystals. The inner core 50 may also be composed of10 wt. % to 30 wt. % piezo polymeric material, and 5 wt. % to 20 wt. %carbon nanotubes. The outer layer 55 may also be composed of 70 wt. % to95 wt. % piezo polymeric material, and 5 wt. % to 20 wt. % carbonnanotubes. The inner core 50 may have a radius ranging from 10 μm to 80μm, while the outer layer 55 may have a thickness ranging from 4 μm to30 μm. The exterior surface of the wire may include a dielectric polymerlayer. The dielectric polymer can be polydimethylsiloxane (PDMS). FIG.16 depicts a plurality of wires, which may each have a multilayeredstructure having compositions described with reference to FIG. 15.

In another embodiment, the neuron-computer bi-directional interfacestructure may be provided by a paste geometry that enables applicationof the material into voids, which can be across non-linear pathways. Thepaste may be applied in a three layered paste that includes an innerlayer a middle layer and an outer layer. The inner layer may be referredto as a core paste material and may include a composite material ofpiezo polymeric material, piezo nanocrystals, and carbon nanotubes. Inone example, the piezo polymer may be present in the core layer in anamount ranging from 10 wt. % to 30 wt. %, the piezo nanocrystals may bepresent in the core layer in an amount ranging from 70 wt. % to 89.9 wt.%, and the carbon nanotubes may be present in an amount ranging from 0.1wt. % to 1 wt. %. In one example, the piezo polymer may be present inthe middle layer in an amount ranging from 70 wt. % to 84.9 wt. %, thepiezo nanocrystals may be present in the core layer in an amount rangingfrom 15 wt. % to 30 wt. %, and the carbon nanotubes may be present in anamount ranging from 5 wt. % to 20 wt. %. The piezo polymer material forthe paste is similar to the piezo polymer material 5 that is describedabove with reference to FIG. 1. Similarly, the piezo nanocrystals andthe carbon nanotubes for the paste are similar to the piezo nanocrystals10 and the carbon nanotubes 15 that are described above with referenceto FIG. 1.

The outer layer of the paste may be include a mixture of a dielectricpolymer and a piezo polymer. For example, the piezo polymer for theouter layer may be polyvinylidene fluoride trifluoroethylene(PVDF-TrFE). In some embodiments, the dielectric polymer for the outerlayer may be polydimethylsiloxane (PDMS). In some embodiment, themixture of the dielectric polymer and the piezo polymer may includepiezo polymer in an amount ranging from 20 wt. % to 60 wt. %, anddielectric polymer in an amount ranging from 70 wt. % to 90 wt. %. Insome embodiments, the mixture of the dielectric polymer and the piezopolymer may include metal nanoparticles in an amount ranging from 30 wt.% to 60 wt. %. The metal nanoparticles may composed of any metal, suchas gold (Au), platinum (Pt), iridium (Ir) or combinations thereof. Insome embodiments, the mixture of the dielectric polymer and the piezopolymer may include carbon nanotubes in an amount ranging from 5 wt. %to 20 wt. %. In yet another embodiment, the outer layer may include aplurality of pores to provide a porous structure.

The piezo polymer material is similar to the piezo polymer material 5that is described above with reference to FIG. 1.

In some embodiments, at least some elements of some of the interfacestructures described with reference to FIGS. 1-16 can be manufacturedusing pixilation and target doping, 3D printing, digital projectionprinting, lamination, hot press technology, and combinations thereof.The piezo polymeric material that provides the matrix for a number ofthe aforementioned polymers may be produced by spin casting from slurry;spray-pyrolysis; directed polymerization; molecular layer epitaxy (MLE)methods, self-assembled solid-state mixtures, and combinations thereof.

The structures depicted in FIGS. 1-16 are piezo-electric materialstructures, each with dimensions from nano-to-micro scale, whichgenerate electrical impulses during any movement due to displacements ofthe piezo-electric material in respect to polymer matrix and/or bendingof the piezo-electric crystals. The electric impulses are generated fromthe movement of said polymer-piezo-electric element system. Allnano-to-micro electrodes operate in parallel, so the resulting power isaccumulating from each electrode.

Being implanted in biological system, the electric charges are to begenerated during the movement: walking, physical activity, head noddingand other like movements. The interface structures described herein canprovide for neuronal stimulation at energies lower than in the currentlyavailable. Such lower output “power” is estimated to be sufficient tofacilitate the cellular physiological functions in excitable cells (e.g.neurons). For example, the density of piezo-electric material in thepolymer can be about 10²-10⁴ piezo-electric elements per 1 mm² of thepolymer matrix. In other examples, it is estimated that the compositematerial described with reference to FIGS. 1-16 when having dimensionsof 250×200×3 mm will produce a converted output voltage and currentsignals at about ˜10 V and 1.3 μA, respectively, showing stability anddurability without degeneration under the repeated bending cycles.

In some embodiments, the proposed technology, as described in theinterface structures 100, 100 a, 100 b, 100 c, 100 d, 100 e, 100 f, 100g, 100 h, 100 i, 100 j, 100 k, 100 l, as depicted in FIGS. 1-16, operatein pseudo-continuous regime, in which the electrical impulses aregenerated each time the position of the piezo-structures (or theirparts) changes in space. This is in dissimilarity with the impulseoperation mode of the contemporary neuro-stimulatory technologies anddevices.

In some of the above described embodiments, in order to amplify theelectric charge generation (if needed), an thin (nano-scale) crystallayer with piezo-electric properties is placed on the outer surface ofthe polymer device. The nano-porous thin layer of piezo-polymer will beplaced as an inner layer of the 2D structure (or in the center of the 3Dstructure). This polymer layer contains carbon nano-tubes in order tofacilitate a small molecule (water and ions) exchange between thepiezo-electric composite material and a neuron, and the extracellularspace. The increase of the CNT concentration in polymer mixture leads tothe increase of the electrical conductivity, thus negating thepiezo-electric properties. In some embodiments, the nano-porous thinlayer of piezo-polymer of carbon nano-tubes may be deposited as an innerlayer for adsorption in order to facilitate the ion exchange withpiezo-electric composite material, and for the removal of the freeradicals (e.g. O₃ ⁻ from the extracellular environment).

In some embodiment, the nano-polymer matrix, e.g., composite materialthat provides the sponge identified as interface structure 100 i in FIG.13, and the three dimensional blot identified as interface structure 100g in FIG. 14, may have nano-porous material layer, providing an ionexchange between piezo material and extracellular compartment. Thisproperty will facilitate the removal of the O₃ ⁻ ions and otheraggressive Oxygen derived free radicals from the vicinity of theelectrode and from the extracellular compartment.

This nano-porous thin layer of neutral polymer or carbon nano-tubes maybe deposited as an outer layer for adsorption in order to facilitate theion exchange with piezo-electric composite material, and the removal ofthe free radicals (e.g. O₃ ⁻) from the extracellular compartment. Thislayer is composed of nano-porous Graphene enriched with Fe/Co—N activesites.

The interface structures 100, 100 a, 100 b, 100 c, 100 d, 100 e, 100 f,100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depicted in FIGS. 1-16can provide biocompatible sustainable self-powered bi-directionalneuron-silica interface technology that can be integrated in theneuron-glial network.

The proposed interface structures 100, 100 a, 100 b, 100 c, 100 d, 100e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depicted inFIGS. 1-16 generate electric impulses via piezo-electric effect innano-crystals through mechanical movement. The applications of thesecharges are vast—electro-stimulation of any excitable tissue (e.g.neurons, Deep Brain Stimulation for Parkinson's disease.

The proposed structures are bi-directional functional neuron-silicainterfaces, in which manipulating the surface charges generated by thedevice based on the piezoelectric effects described above can providefor communication to a natural neuron or neuronal network. At the sametime, the bi-directional functional neuron-silica interfaces is able to“read” the changes on the surface of the natural neuron. The potentialapplications of such technology are vast, e.g., all types and kinds ofneuro-prosthetics and brain-computer interface with machine learning,feedback, etc.

The neuron-computer bi-directional interface structures, i.e., interfacestructures 100, 100 a, 100 b, 100 c, 100 d, 100 e, 100 f, 100 g, 100 h,100 i, 100 j, 100 k, 100 l that are depicted in FIGS. 1-16, can be usedfor brain-computer interface and local electro-stimulation. In someembodiments, the neuron-computer bi-directional interface structuresgenerate the electricity locally, with no wires, and no externalbattery. Further, the neuron-computer bi-directional interface structureare biocompatible, i.e., not just a neutral material, but a compositematerial, which will be accepted by neurons as a familiar environmentdue to it's naturalistic surface properties. It will be able to generateelectrical impulses inside itself and accumulate charges on its surface.These charges will be of the same scale as “natural” charges on thesurface of a natural neuron.

In some embodiments, because of the biocompatibility it is anticipatedthat the interface structures described herein will work in much lowervoltages than conventional devices. For example, the interfacestructures might be a “circle”—low voltage, which equates to betterbiocompatibility, which in turn, makes the tissue more susceptible forlower voltages. In some embodiments, to make biocompatibility evenbetter we have a “feature” of accepting free radicals (H₂O₂ and otherspecies), degrade it to H₂O and HCO₃— (or CO₂) and an electron (whichwill be used for re-charging piezo-elements). This anti-oxidant effectis also adding to enhanced biocompatibility.

In the context of neurodegenerative disease, where neurons areprogressively dying and the neuronal network is therefore disrupted, theinterface structures provided herein can offer the surviving neurons asubstrate that looks like neurons and feels like neurons. Similarly, incases where the neuronal network is disrupted by other mechanism such astrauma, inflammation/demyelination, or malformation. The survivingneurons will react to our artificial neuron in a “friendly andaccepting” manner, and charges that are generated in an “artificialneuron” via piezo-electric effect will be picked up by surviving neuronsand facilitate/augment their function. This will help to restore theneuronal network, which was the damaged by the disease or trauma.

In one example, the above described neuron-computer bi-directionalinterface structures will be able to remove free radicals (oxygenspecies, e.g. O3- ions) from extracellular compartment, thus decreasingthe oxidative stress and lipids' peroxidation, including cellularmembranes and myelin.

The interface structures 100, 100 a, 100 b, 100 c, 100 d, 100 e, 100 f,100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depicted in FIGS. 1-16are creating an interface between an electrode and a neuron (or neuronalnetwork). This interface will be bi-directional. Manipulating thecharges generated by the artificial neuron provides for communicationwith the natural neuron or neuronal network. At the same time, theinterface structures can read the changes on the surface of the naturalneuron.

The interface structures 100, 100 a, 100 b, 100 c, 100 d, 100 e, 100 f,100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depicted in FIGS. 1-16may be devices can be autonomous (no wires to the computer) or wired tothe computer. The autonomous devices can: (i) harvest mechanical energy;(ii) transform in to the electrical impulses; (iii) deliver impulses toneuronal network locally. The activity of the autonomous devices can beregulated via external magnetic field. This mechanism is related to the“poling”. The interface structures 100, 100 a, 100 b, 100 c, 100 d, 100e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depicted inFIGS. 1-16 devices can also be non-autonomous devices. Non-autonomousdevices can be regulated via wires as any other wired devices. For anon-autonomous device, the interface structures 100, 100 a, 100 b, 100c, 100 d, 100 e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k, 100 l thatare depicted in FIGS. 1-16 may be employed as the leads/electrodes.

In some embodiments, the surface of the interface structures 100, 100 a,100 b, 100 c, 100 d, 100 e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k,100 l that are depicted in FIGS. 1-16 act as a low-voltage sensor: thesignal from a neuron is “sensed” by the outer layer, transferred to thedeeper layers, and amplified in the layers with high concentration ofcrystals, and transferred via wires to the computing device, e.g.,machine learning, prosthetics, robotics, etc.

The interface structures are designed to be low voltage biocompatiblesurface, in which the charges/impulses are adjusted to the range neuronsgenerate naturally (action potential range).

In some embodiments, the in situ electro-stimulation that can beprovided by the interface structures 100, 100 a, 100 b, 100 c, 100 d,100 e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depictedin FIGS. 1-16 will not only augment the neuronal network function, butalso facilitate neuronal neurogenesis and the increase of the dendriticdensity. Overall advantages can include facilitation and maintenance ofexisting neuronal network, re-wiring via axonal sprouting and theincrease of the dendritic density, neurogenesis stimulation/facilitationand a new neuronal network formation.

In some embodiments, the impulses generated by the nano-structuresincluded in the interface structures 100, 100 a, 100 b, 100 c, 100 d,100 e, 100 f, 100 g, 100 h, 100 i, 100 j, 100 k, 100 l that are depictedin FIGS. 1-16 can be modified and/or amplified with a powerful magneticfield, both constant (static) and/or variable, thus providing anexternal control over the device.

For example, the piezo-electric composite polymer-crystal material hasferromagnetic properties. In order to compensate the possiblepolarization in the high-energy magnetic field (e.g. MRI machines) andto make our material magnetically neutral, spintronics technology (spintransport electronics) can be employed. The spintronics technologycomprises two ferromagnetic layers separated with the carbon nano-tubedielectric layer. In one option, i.e., option one, the ferromagneticlayers will undergo polarization without any external magnetic fieldbefore the assembly of the composite material. While in the Constant(Static) or Variable magnetic field only a very small fraction of spinswill get synchronized, thus the resulting direction of the impulses willoverall remain random.

In a second option, the ferromagnetic layers can be polarized in thesame magnetic field. In such option of the composite material, theresulting impulses will be amplified being further exposed to theexternal magnetic field. The direction of generated piezo-electricimpulses can be manipulated by the tuning of the external magneticfield. The direction of impulses can by synchronized, allowing thediode-like effect. This technology provides for a desired number ofimpulses to the desired direction in optimizable patterns.

In a third option, the ferromagnetic layers undergo polarization in themagnetic fields of opposite directions separately, before the assemblyinto the composite material; and, therefore, being assembled with adielectric layer in between, will compensate the external magneticfield. Giant Magnetoresistance (GMR) is then applied to the structure.This option provides that the composite material is magnetically neutralin the external high-energy magnetic fields (e.g. MRI machines). Thegenerated piezo-electric impulses are3 distributed at random without theexternal magnetic field. The external Constant (Static) magnetic fieldwill lock the impulses. The Variable magnetic field will synchronize thespins accordingly, but the direction of the impulses will remain random.Two variants of GMR that can be employed with the composite structuresdescribed above with reference to FIGS. 1-16 include: (1)current-in-plane (CIP), where the electric current flows parallel to thelayers and (2) current-perpendicular-to-plane (CPP), where the electriccurrent flows in a direction perpendicular to the layers. Options twoand three of the above described spintronics technology can provide acomposite material can be also viewed as a sensitive magnetic fieldsensor.

Although the invention has been described generally above, the followingexamples are provided to further illustrate the present invention anddemonstrate some advantages that arise therefrom. It is not intendedthat the invention be limited to the specific examples disclosed.

Examples

Four example compositions were formed for testing. Composite 1 was apiezoelectric composite that was composed of 20% piezoelectric crystals(Pb(Mg_(1/3)Nb_(2/3))O₃—PbTiO₃ (PMN-PT)); 79% piezoelectric polymerPVDF-TrFE and 1% carbon nanotubes (CNTs). Composite 2 was apiezoelectric composite including 70% piezoelectric crystal(Pb(Mg_(1/3)Nb_(2/3))O₃—PbTiO₃ (PMN-PT)); 29% piezoelectric polymerPVDF-TrFE and 1% CNT. Composite 3 was a three layered structureincluding a core layer having the composition of composite 2 and outerlayers having the composition of composite 1. Composite 4 was a threelayered structure including a core layer having the composition ofcomposite 1 and outer layers having the composition of composite 2. Forcomposite 4, the core layer was sprayed with 0.5 ml of Dimethylformamideto improve adhesion between layers.

All composites underwent poling under the following conditions:Temperature: 50° C., Voltage: 4000-10 000V and Time: 3-10 minutes.

The piezoelectric charge coefficient was measured for composites 1, 2,and 3; and the piezoelectric voltage coefficient was measured forcomposites 1 and 2 The piezoelectric charge coefficient d₃₃ forcomposite 1 was equal to 30 pC/N; and the piezoelectric chargecoefficient d₃₃ for composite 2 was equal to 31 pC/N; and thepiezoelectric charge coefficient d₃₃ for composite 3 was 30 pC/N. Thepiezoelectric voltage coefficient g33 for composite 1 was equal to 14.3mV*m/N; and the piezoelectric voltage coefficient g33 for composite 2was equal to 16.5 mV*m/N.

Further, the composite multilayered materials showed increasedpiezoelectric coefficients. For example, the piezoelectric chargecoefficient d33 increases from measures ˜280 pC/N in Composite 1compared to ˜320 pC/N in Composite 3. The piezoelectric voltagecoefficient g33 increased from measures ˜14 mV*m/N in Composite 1compared to ˜17 mV*m/N in Composite 3.

The composite materials showed the following piezoelectric effect (CH1)parameters in mono-layered compared to multi-layered configurations:

10 Hz oscillations: Composite 1=156 mV

10 Hz oscillations: Composite 3=240 mV

Having described preferred embodiments of a self-powered bi-directionalneuron-electronic device interface technology (which are intended to beillustrative and not limiting), it is noted that modifications andvariations can be made by persons skilled in the art in light of theabove teachings. It is therefore to be understood that changes may bemade in the particular embodiments disclosed which are within the scopeof the invention as outlined by the appended claims. Having thusdescribed aspects of the invention, with the details and particularityrequired by the patent laws, what is claimed and desired protected byLetters Patent is set forth in the appended claims.

1. An interface structure for a biological environment comprising: atleast one composite electrical impulse generating layer comprising amatrix phase of a piezo polymer material, a first dispersed phase ofpiezo nanocrystals, and second dispersed phase of carbon nanotubes, thefirst and second dispersed phase presented through the matrix phase,wherein the piezo polymer material and piezo nanocrystal convertmechanical motion into electrical impulses and accept electrons tocharge the composite impulse generating layer, and the carbon nanotubesprovide pathways for distribution of the electrical impulses to asurface of the composite impulse generating layer contacting thebiological environment, and delivery of byproducts of free radicalsdegradation from the biological environment to both piezo-nanocrystalsand piezo-polymer material.
 2. The interface structure of claim 1,wherein at least one biological environment interface layer is incontact with the surface of the composite impulse generating layer toprovide a multi-layered interface structure, the electrical impulsesreaching the surface of the composite impulse generated layertransmitted by biological environmental interface layer to stimulatecells in the biological environment.
 3. The interface structure of claim1, wherein the at least one biological environmental interface layer isprovided by a grid geometry comprised of a metal selected from the groupconsisting of gold, silver, platinum, iridium, and combinations thereof,the composite impulse generating layer includes the piezo polymerpresent in a wt. % ranging from 10%-99.9%, the piezo nanocrystalspresent in a wt. % ranging from 15%-99.9%, and the carbon nanotubespresent in a wt. % ranging from 0.5% to 1%.
 4. The interface structureof claim 3, wherein the interface structure has a two dimensional formfactor having a geometry of a ribbon, a sheet or a combination thereof.5. The interface structure of claim 4, wherein the interface structurefurther comprises at least one composite electrical impulse amplifyinglayer comprising an amplifying matrix phase of the piezo polymermaterial, a first dispersed phase of the piezo nanocrystals, and seconddispersed phase of the carbon nanotubes, the first and second dispersedphase presented through the amplifying matrix phase, wherein thecomposite impulse amplifying layer has a higher piezoelectriccoefficient than the composite impulse generating layer, the compositeimpulse amplifying layer receiving electrical impulses from saidcomposite impulse generating layer and increasing said magnitude ofcharge of said electrical impulses, and transmitting to the at least onebiological environmental interface layer.
 6. The interface structure ofclaim 5, wherein the composite impulse amplifying layer including saidpiezo polymer material present in a wt. % ranging from 10% to 30%, thepiezo nanocrystals present in a wt. % ranging from 70% to 89.0%, and thecarbon nanotubes present in a wt. % ranging from 0.1 to
 1. 7. Theinterface structure of claim 6, wherein the at least one compositeimpulse generating layers includes two composite impulse generatinglayers, wherein one said two composite impulse generating layers ispresent on opposing sides of the composite impulse amplifying layer toprovide a cascade amplification of a piezoelectric effect resulting fromstress-dependent change in polarization.
 8. The interface structure ofclaim 7, wherein the at least one biological environmental interfacelayer comprises two grid structures on opposing sides of a materialstack that provides the interface structure including the at least onecomposite impulse generating layers and the at least one compositeimpulse amplifying layers.
 9. The interface structure of claim 6,further comprising an bilayer of a resin layer and a piezoelectriccomposite layer free of carbon nanotubes, wherein the bilayer ispositioned between the biological environmental interface layer and thecomposite impulse amplifying layer so that the resin layer is in contactwith the biological environmental interface layer and the piezoelectriccomposite layer free of carbon nanotubes is in contact with thecomposite impulse amplifying layer.
 10. The interface structure of claim9, wherein the resin layer provides for K—Na ion exchange byfacilitating charge delivery, and is comprised of sulfonated poly etherether ketone (SPEEK) incorporated with micron-sized sulfonatestyrene-crosslinked divinyl benzene-based cation exchange resinparticles.
 11. The interface structure of claim 10, wherein thepiezoelectric composite layer free of carbon nanotubes comprises amatrix phase of piezo polymer present in the piezoelectric compositelayer in a wt. % ranging from 10% to 30%, and a dispersed phase of piezonanocrystal present throughout the matrix phase, and is present in thecomposite in a wt. % ranging from 70% to 90%.
 12. The interfacestructure of claim 1, further comprising a dielectric polymer layerabutting the composite impulse generating layer.
 13. The interfacestructure of claim 1, wherein the interface structure has a threedimensional form factor selected from a substantial sphere, asubstantial sphere with projections, a sponge, a wire, a dendriticstructure, paste and combinations thereof.
 14. The interface structureof claim 1, wherein the piezo polymer material has a composition that isselected from the group consisting of polyvinylidene flouride (PVDF),polyvinylidene fluoride (PVDF) copolymer with triflourethylene (TrFE),polyvinylidene fluoride (PVDF) copolymer with tetrafluorethylene (TFE),polyvinylidene fluoride (PVDF) copolymer with tetrafluorethylene (TFE)and triflourethylene (TrFE), nylon 11, poly(vinylidenecyanidevinylacetate), and combinations thereof.
 15. The interface structure ofclaim 1, wherein the piezo polymer material is polyvinylidene fluoridetrifluoroethylene having a beta (β) phase.
 16. The interface structureof claim 1, wherein the piezo nanocrystal is a piezo ceramic materialhaving crystals with a composition selected from the group consisting oflead zirconate (PbZrO₃), lead titanate (PbTiO₃), and combinationsthereof.
 17. The interface structure of claim 1, wherein the piezonanocrystal has a wire type geometry.
 18. The interface structure ofclaim 1, wherein the piezo nanocrystals are a single crystalpiezoelectric having the composition (1-χ)PbZn_(1/3)Nb_(2/3)O₃-χPbTiO₃(PZNT).
 19. The interface structure of claim 1, wherein the piezonanocrystals are of a composition selected from the group consisting ofLi-doped (K, Na)NbO₃, Ba(Ce_(x)Ti_(1-x)O3), and a combination thereof.20. The interface structure of claim 1, wherein the carbon nanotubescomprise single wall carbon nanotubes or multiwall carbon nanotubes.